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Tooth Eruption and Shedding

Presented by; Binaya BhandariBDS, final yearKUSMS , NEPAL

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Contents

• Introduction of eruption• Phases of eruption• Theories of eruption• Mechanism of resorption and shedding• Chronology of human dentition• Teething and teething problems• Management of teething problems• Conclusion• References

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Eruption

• Eruption is defined as a process whereby the forming tooth migrates from its intraosseous location in the jaw to its functional position within the oral cavity. [ Maury Massler and Schour, 1941 ]

• It is catagorized into three phasesPhase 1 : The pre-eruptive phasePhase 2 : The eruptive phasePhase 3 : The post-eruptive phase

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1. Pre-Eruptive phase

- Preparatory phase

- Movement of developing tooth germs within alveolar processes

prior to root formation

- Bodily movement - Eccentric growth

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2. Eruptive phase Noyes and Schour;

Stage 1 : Preparatory stage (Opening of bony crypts )

Stage 2 : Migration of tooth towards the oral epithelium

Stage 3 : Emergence of crown tip into the oral cavity

Stage 4 : First occlusal contactStage 5 : Full occlusal contactStage 6 : Continuous eruption

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The rate of tooth eruption depends on the type of movement

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•1 to 10 µm/dayINTRAOOSEOUS

PHASE

•75 μm/dayEXTRAOSSEOUS

PHASE

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3. Post- Eruptive phase

• movements made by the tooth after it has reached its functional position in the occlusal plane.

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Accommodation for growth

Compensation for occlusal wear

Accomodation for interproximal wear

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• ACCOMMODATION FOR GROWTH - Mostly occurs between 14 and 18 years by formation of new bone at the alveolar crest and base of socket to keep pace with increasing height of jaws.

• COMPENSATION FOR OCCLUSAL WEAR - Compensation

primarily occurs by continuous deposition of cementum around the apex of the tooth. However, this deposition occurs only after tooth moves.

• ACCOMMODATION FOR INTERPROXIMAL WEAR - Compensated by mesial or approximal drift.

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Theories of Tooth eruption

• Root elongation theory• Pulpal constriction theory• Growth of periodontal tissues• Pressure from muscular action• Resorption of alveolar crest• Hormonal theory• Foreign body theory• Cellular proliferation theory• Vascularity theory• Blood vessel thrust theory• Periodontal ligament contraction theory• Dental follicle theory• Bone remodelling theory

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1. Root elongation theory

• Simplest and most obvious mechanismGrowth and elongation of roots

Teeth pushed into the oral cavity

Evidence against this theory;-Rootless teeth-submerged teeth

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2. Pulpal constriction theory

Growth of root dentin and constriction of pulp

Tooth moves occlusally

pressure

Evidence against this theory;-Pulpless teeth

- Permanent premolar jump

into occlusion after premature extraction of decidious molar

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3. Growth of periodontal tissue

-Teeth is pulled by surrounding connective tissue

-Alveolar bone growth

Evidence against this theory;- Histologically; Periodontal fibers are being pulled by tooth and not

vice versa-Radiographically/Histologically ; Bone doesn’t actually touch the

tooth

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4. Pressure from muscular action Musculature of cheek and lips

upon alveolar process

Squeeze the crown of tooth out in oral cavity

Evidence against this theory;- Teeth even erupts in cases of

unilateral facial paralysis

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5. Resorption of alveolar crestResorption of alveolar crest

Expose the crown of the tooth in oral cavity

Evidence against this theory;-Histologically; alveolar crest is the site of most rapid and continuous

growth of bone

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6. Hormonal theory

Hormones secreted by thyroid and pituitary gland

Govern eruption of teeth

Evidence against this theory;- Doesn’t explain the mechanism of

teeth eruption

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7. Foreignbody theory

Calcified body such as tooth tends to be exfoliated by tissues just as

does any foreign body

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8. Cellular proliferation theory

Cellular proliferation of pulpal and surrounding tissues

Increased osmotic pressure and forces

Eruption of teeth

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9. Vascularity theory

Rich vascular supply between teeth and its bony surroundings

Increased pressured by vessels

Eruption of teeth

- Hyperemia; even submerged teeth erupts

- Hyperemia in periodontitis- supraeruption of teeth

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10. Blood vessel thrust theory

Blood supply to the teeth

Hydrodynamic and hydrostatic forces within blood vessels

Eruption of the teeth

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11. Periodontal ligament contraction theory

Shrinking and crosslinking of fibroblast within periodontal

liagament

Traction forces like locomotion

Eruption of teeth

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12. Dental follicle theory Reduced enamel epithelium

cascade of intercellular signals

recruits osteoclast to the follicle

bone remodelling

erution of teeth

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13. Bone remodelling theoryBone remodeling

The growth pattern of the maxilla and the mandible moves teeth by selective deposition and resorption of bone.

Major proof is when a tooth is removed without disturbing its follicle tooth germ, an eruptive pathway still forms within bone as osteoclasts widen the gubernacular canal.

If the dental follicle is also removed no eruption path develops.

It establishes absolute requirement for a dental follicle to achieve bony remodeling and tooth eruption.

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Shedding of Decidious teeth

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Shedding of Decidious teeth

• shedding or exfoliation of deciduous teeth is a term given to describe the physiologic process that ultimately leads to replacement of the deciduous teeth by their corresponding permanent successors

• resorption with permanent sucessor• resorption with out permanent sucessor

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Resorption with permanent sucessor

Anterior teeth resorption with permanent sucessor

-Resorption of lingual surface of apical third of primary tooth root.-Resorption of labial surface.-Resorption proceeds horizontally in incisal direction until primary tooth sheds & permanent tooth erupts.

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Resorption with permanent sucessor

Posterior teeth resorption with permanent sucessor

-The growing crown of the permanent posterior teeth are

situated between the roots between primary molars

- Initiation is by resorption of inter-radicular bone followed by

resorption of the adjacent surfaces of the root of primary

tooth

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Resorption without permanent sucessor

• The root is protected from resorption by presence of narrow PDL cell layers which are composed of:

- Collagen fibers - Fibroblasts - Cementoblasts

• Degradation of PDL precede root resorption & removal of collagen fibers of PDL is considered main step in initiation of this process.

• As face grows & muscles of mastication enlarge, forces that are applied on the deciduous teeth become heavier than periodontal ligament can withstand primary tooth .

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Problems associated with sheddingRemnant of decidious dentition;

-parts of the root of decidious teeth embeded in jaw for

considerable time

-frequently found in association with permanent premolars

because the roots of lower 2nd decidious molars are strongly

curved or divergent

Retained decidious teeth;- Absence of permanet sucessor - impacted permanent sucessor

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Nolla’s stage of teeth eruption,1952

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Chronology of human dentitionSequence of primary teeth eruptionMaxillary arch ; A-B-D-C-EMandibular arch ; A-B-D-C-E

Sequence of permanent teeth eruptionMaxillary arch ; 6-1-2-4-5-3-7Mandibular arch; 6-1-2-3-4-5-7

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Chronology of human dentition

7 ½9 1814 24

20121676

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Chronology of human dentition

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Importance of primary teeth

-Chewing on well-formed teeth helps the jaw bones to grow and develop properly.

-provide proper space for the eruption of permanent teeth.

-are necessary for proper chewing of food, and normal digestive processes.

-are also necessary for learning speech sounds and proper language development.

-Healthy baby teeth are also important for a child's self-esteem and well being

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Problems associated with primary teeth eruption

• Teething• Eruption cyst• Eruption sequestration• Ectopic eruption• Non-eruption• Natal and neonatal teeth

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Signs and symptoms of teething; -Pain

-Inflammation of mucous membrane

-General irritability/malaise-Disturbed sleep/wakefulness

-Facial flushing/ circumoral rash-Drooling/sialorrhea

-Gum rubbing/biting/sucking-Constipation/diarrhea

-Loss of appetite-Ear rubbing

Management

Non pharmacological-Teething rings (chilled)

-Hard sugar-free teething rusks-cucumber (peeled)

- Frozen items like bananas, vegetables - Pacifiers

- Rub gums with clean finger, wet guaze- Reassurance

Pharmacological-Analgesic/antipyretics

-Topical anesthetic agents-Alternative holistic medicine

Teething .. Process of eruption of first teeth into the oral cavity

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Steward’s approch to teething

• 1st approach – give the child freezed teething rings to bite - greatest relief

• If pain is troublesome, give appropriate dose of sugar free paracetamol elixir every 4-6 hourly

• Additional analgesia – lignocaine based teething gels

Paracetamol3-12 months = 60-120 mg

1-5 years = 120-150 mg

Lignocaine7.5mm of gel should be

placed on a clean finger or cotton bud, and rubbed into

painful areas.

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Teething problems

-Eruption hematoma-Eruption sequestratrum-Ectopic eruption-Natal and neonatal teeth-Non eruption teeth

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Eruption hematoma (eruption cyst)

- blood filled cyst -bluish purple, elevated area of tissue-occasionally develops few weeks before eruption of primary/permanent dentition-results due to trauma to soft tissue during function-subsides after eruption of teeth-common area; primary 2nd molar or permanent 1st molar region

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Eruption hematoma (eruption cyst)

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Eruption sequestrum

-ocasionally seen in the children at the time of eruption of 1st permanent molar

-composed of cementum like material formed within the dental follicle

-Hard tissue fragments is generally overlying the central fossa of associated embedded tooth and contoured of soft tissue

-as tooth erupts, the cusp emerge the fragment sequestrates -usually little or no clinical significance

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Ectopic eruption

- due to arch length inadequacy or a variety of local factors

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Natal and neonatal teeth

• -Teeth if present at birth – natal teeth-Teeth if present within thirty days of life – neonatal teeth [ Massler and Savara, 1950]

Clinical appearance -most commonly affected -

lower primary central incisor- normal teeth to poorly

developed, small, conical, yellowish, white hypoplastic

enamel or dentin and underdeveloped root

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Natal and neonatal teeth

Etiology

- Hypovitaminosis- Hormonal stimulation

- Trauma- Febrile states

-Syphilis

[current concept – superficial position of the developing tooth germ predisposes tooth to erupt

early]

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Natal and neonatal teeth

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Natal and neonatal teeth

Management;

-Radiograph : amount of root development

-Topical chlorhexidine application: inflammed gingiva around teeth

-Selective grinding of teeth : sharp incisal edge

- Removal of hypermobile teeth : avoid risk of aspiration

-Curettage of socket after extraction : remove any

odontogenic cellular remnants

Complications;

-Traumatic ulceration on the ventral surface of the tongue,

frenum or lips, ulceration on the sublingual area.

-Riga and Fede 1881, 1890 decribed “Riga – Fede disease”

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Non-eruption of teeth

Noneruption teeth;

In case of non eruption of teeth beyond their common schedule

Advisable to give a minor incision to facilitated their eruption if they are

no associated with impaction or pathologies

Local causes:

-mucosal barrier-supernumerary teeth

-injuries to primary teeth

Genetic causes :

-Gardner syndrome-Cleidocranial dysplasia

Endocrinal causes :

-Hypothyroidism-Hypoparathyroidism

-Hypopituitarism

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FACTS

• Why primary teeth are called milk teeth?

- Milk teeth are called so due to their white color which resembles the color of milk. The milk teeth are whiter than the permanent teeth which replace them. The refractive index of milk teeth is 1.338, similar to that of milk and hence they are called so.

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FACTS

• Why there is no bleeding on eruption of teeth?

-Reduced enamel epithelium unites with the oral epithelium.

- REE has no blood supply, As the cells of the reduced enamel epithelium degenerate, the tooth is revealed

- The crown breaks the double layer epithelium overlying it and enters the oral cavity

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FACTS

• Accelerating factors

- Hyperthyroidism-Hperparathyroidism-Hyperpituitarism

• Decelerating factors

-Hypothyroidism-Hypoparathyroidsm-Hypopituitarism

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Conclusion

• For the clinicians to treat dental problems knowledge of proper eruption time is very important .

• A variety of developmental defects that are evident after eruption of the primary and permanent teeth can be related to local and systemic factors.

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References ;

• Textbook of pediatric dentistry- 3rd edition- Nikhil marwah

• Textbook of pedodontics – 2nd edition – Sobha Tandon• http://www.healthunit.org/dental/children_oral/prim

ary_teeth_facts.htm

• http://www.32teethonline.com/pediatric-dentistry-teeth-dental%201.htm

• https://www.google.com/search.wikepedia • http://www.hindawi.com/journals/scientifica/2014/34

1905/• http://phpa.dhmh.maryland.gov/oralhealth/docs1/fac

t_sheets/Infant_and_Toddler_OH-teething.pdf• https://dentalpguploads.wordpress.com/2013/05/06/

nollas-stage-of-tooth-eruptionaiims-12/

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